fix(scripting+alarms): close remaining re-review findings

Single commit covering the four small/medium fixes from the updated
code review.

Core.Scripting-014 (Medium, Concurrency):
  CompiledScriptCache.Clear() used the key-only TryRemove(key, out var
  lazy) overload — same race shape Core.Scripting-006 closed in
  GetOrCompile's catch block. A concurrent re-add between snapshot and
  TryRemove was evicted + disposed while the new caller still held it.
  Replaced with the value-scoped TryRemove(KeyValuePair<,>) overload.
  Regression test
  Clear_uses_value_scoped_TryRemove_so_a_race_inserted_entry_survives
  added.

Core.Scripting-013 (Medium, Security):
  Hand-rolled BuildWrapperSource pastes user source between literal
  braces; brace-balanced source could inject sibling methods/classes
  alongside CompiledScript.Run. Analyzer still walked the injected
  members so it wasn't a direct escape, but it relaxed the documented
  'method body' authoring contract. Added EnforceSingleRunMember:
  after ParseText, the compilation unit must hold exactly one type
  (CompiledScript) and that type must hold exactly one member (the Run
  method). Any deviation throws CompilationErrorException with LMX001/
  LMX002 diagnostic IDs and a Core.Scripting-013 reference in the
  message. Two regression tests added covering the sibling-method and
  sibling-class injection vectors.

Core.Scripting-015 (Low, Correctness, latent):
  ToCSharpTypeName's generic branch truncated at the first backtick via
  IndexOf, silently dropping closed args of nested-generic shapes
  (Outer<T>.Inner<U>). No production caller exercises this shape today
  (all TContext/TResult are top-level non-nested), so the bug was
  latent. Rewrote the generic branch to walk the FullName segment-by-
  segment, consuming generic args per segment so nested shapes emit
  valid C# (global::Ns.Outer<T>.Inner<U> rather than the broken
  Outer<T,U>).

Core.ScriptedAlarms-013 (Low, Documentation):
  The internal test accessors TryGetScratchReadCacheForTest /
  TryGetScratchContextForTest return live mutable scratch refilled in
  place under _evalGate. XML docs didn't warn future test authors about
  the synchronization contract. Added a <remarks> block to each
  documenting the only-safe-on-quiesced-engine + identity-or-single-key
  contract.

Verification (suites green):
  Core.Scripting.Tests: 110/110 (was 107 — +3 new rejection/race tests)
  Core.ScriptedAlarms.Tests: 67/67 (unchanged — doc-only fix)
  Core.VirtualTags.Tests: 57/57 (unchanged)

After this commit, all 12 findings from the updated re-review are
closed (10 Resolved, 1 Won't Fix none, 1 Deferred — Driver.Galaxy-017).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Core/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ScriptedAlarmEngine.cs

@@ -83,6 +83,19 @@ public sealed class ScriptedAlarmEngine : IDisposable
     ///     regression tests to assert the scratch is reused across evaluations
     ///     (two reads return the same instance).
     /// </summary>
+    /// <remarks>
+    ///     <b>Synchronization:</b> the returned <see cref="IReadOnlyDictionary{TKey, TValue}"/>
+    ///     is the engine's live mutable read-cache. It is refilled in place by
+    ///     <c>RefillReadCache</c> on every predicate evaluation, under <c>_evalGate</c>.
+    ///     Test callers MUST NOT iterate this dictionary while the engine is
+    ///     actively evaluating (i.e. while an upstream change is mid-flight); the
+    ///     refill clears the dict before repopulating and a concurrent iterator
+    ///     would observe torn / partial state. Safe uses are: reference-identity
+    ///     comparisons (e.g. asserting the same instance is reused across calls),
+    ///     and single-key reads against an engine that has quiesced after a
+    ///     deterministic upstream push. Anything more involved should snapshot a
+    ///     copy under the gate. (Core.ScriptedAlarms-013.)
+    /// </remarks>
     internal IReadOnlyDictionary<string, DataValueSnapshot>? TryGetScratchReadCacheForTest(string alarmId)
         => _scratchByAlarmId.TryGetValue(alarmId, out var s) ? s.ReadCache : null;
 
@@ -91,6 +104,13 @@ public sealed class ScriptedAlarmEngine : IDisposable
     ///     if one has been allocated, else null. Companion to
     ///     <see cref="TryGetScratchReadCacheForTest"/>.
     /// </summary>
+    /// <remarks>
+    ///     <b>Synchronization:</b> the returned context wraps the same live
+    ///     read-cache as <see cref="TryGetScratchReadCacheForTest"/> — the same
+    ///     "don't iterate during an in-flight evaluation" caveat applies. Safe
+    ///     for reference-identity assertions on a quiesced engine.
+    ///     (Core.ScriptedAlarms-013.)
+    /// </remarks>
     internal AlarmPredicateContext? TryGetScratchContextForTest(string alarmId)
         => _scratchByAlarmId.TryGetValue(alarmId, out var s) ? s.Context : null;
     private readonly ConcurrentDictionary<string, DataValueSnapshot> _valueCache